渤海L油田稠油水平井蒸汽吞吐开发效果分析

Thermal recovery effect evaluation of cyclic steam stimulation of heavy oil horizontal wells in Bohai L oilfield

L油田是渤海首个进行稠油蒸汽吞吐热采试验的先导区,对其开发效果准确评价关系着渤海稠油蒸汽吞吐开发技术的推广及应用。基于蒸汽吞吐井实际生产动态数据,对L油田蒸汽吞吐实际注入状况、井底流温、产量、含水及热采增油效果等方面进行分析。结果表明,蒸汽吞吐下泵生产后井底流温较高,高峰达103℃,之后大幅度降低,蒸汽吞吐井底流温提高幅度大于多元热流体吞吐;根据产油量变化,蒸汽吞吐可划分为四个阶段:放喷吐水、高产、快速递减和低产稳定阶段,产量递减符合指数递减规律,第一轮次月递减率为22.3%~28.6%;蒸汽吞吐井第1月平均日产油是冷采井的2.5~2.8倍,第1年平均日产油和累计产油是冷采井的1.7~2.2倍,平均2.0倍。蒸汽吞吐能显著提高渤海稠油开发效果。

L oilfield is the first cyclic steam stimulation(CSS)pilot in Bohai bay.Accurate evaluation of the dynamics and performance of CSS helps to guide and promote the following CSS development technology.The status of injection,bottom hole temperature,oil flow rate,water cut,and incremental oil under thermal recovery of L oil field were analyzed based on CSS well dynamics.The bottom hole temperature after CSS reached 103℃,and then decreased rapidly.The bottom hole temperature obtained from CSS is higher than multithermal fluid stimulation.According to the production rate,CSS production process can be subdivided into four phases:water production phase,peak oil production phase,fast decline phase,and low stabilized oil production phase.The production decline trend follows exponential decline.The first-round monthly decline rate is 22.3%~28.6%.The first month average production rate is as 2.5 to 2.8 times of production under pressure depletion only.The first-year average daily production or the annual production under CSS is 0.7 to 1.2 times higher compared with pressure depletion,with an average of 2.0.CSS can obviously increase the development effect of Bohai heavy oilfield.